Multidegrees‐of‐freedom effective force testing: a feasibility study and robust stability assessment     

Narutoshi Nakata  Erin Krug 《地震工程与结构动力学》2013,42(13):1985-2002

This paper presents a feasibility study of multidegrees‐of‐freedom effective force testing (MDOF‐EFT). The study is intended to facilitate the development of a force feedback controller and investigation of performance as well as robustness of MDOF‐EFT. First, the dynamics of MDOF‐EFT systems are analytically investigated. Analytical transfer functions of the control plant, the valve‐to‐force relations, showed that the plant is dynamically coupled and the natural frequencies of test structures are the transmission zeros of the plant. Using a set of model parameters from a previous study, a case study that includes controller design, numerical simulations and robust stability assessment is performed. A decoupling loop shaping (DLS) controller consisting of a pseudo inverse of the plant and second‐order loop shaping controllers is adopted as the force feedback controller. It is shown that the DLS controller provides a stable control system while successfully decoupling the control loops and compensating the control‐structure interaction. Numerical simulations demonstrate that the DLS controller enables tracking of static and dynamic forces for multiple actuators. Robust stability of MDOF‐EFT with the DLS controller is assessed using Monte Carlo simulation. The stochastic simulation results show that the DLS controller is stable and robust, providing sufficient stability margins for uncertain models with maximum 50% errors in the estimated system parameters. This paper demonstrates that MDOF‐EFT is feasible with the DLS controller and can be implemented in experimental laboratories. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

On the Seddon speed formula     

SURENDRA KUMAR MISHRA  VIJAY P. SINGH 《水文科学杂志》2013,58(3):333-347

Abstract

The Seddon speed formula expressed mathematically as c = dQ/dA (or alternatively, as c = (1 + m)u_o; where Q is the discharge, A is the area of cross-section, c is the wave speed, u_o is the normal flow velocity, and m is a dimensionless parameter) is revisited in the context of elasticity and thermodynamics. Its link with the linearized solution of St Venant's equations for wave celerity, which does not appear to have been reported in the hydrological literature, is established. The rating exponent m is shown to be equivalent to the dimensionless relative celerity and is found to be the ratio of two specific heats, viz. c_p and c_v which are the specific heats at constant pressure and volume, respectively. The use of the parameter m as a complex variable helps describe shallow wave characteristics, the damping capacity of a wave, and the mechanism of occurrence of the hysteretic phenomenon. The damping capacity is found to describe the magnitude of wave subsidence, whereas the hysteresis also describes the speed of subsidence.  相似文献   

速度传感反馈地震计的参数稳定性分析     

杨晓源  邵玉平  杜瑶 《地震地磁观测与研究》2011,32(6):109-115

从理论上定量分析机械摆和环路滤波等开环诸参数变化对速度传感反馈地震计闭环参数的影响.研究指出,在环路设计中可半自由选取的开环阻尼取值对参数稳定性有重要影响.过大或过小的开环阻尼取值均可能造成参数稳定性急剧变差,影响地震计在只标不调的状况下长期连续稳定工作.  相似文献   

同心补偿式直升机时间域航空电磁法吊舱校准装置研究   总被引：3，自引：2，他引：1       下载免费PDF全文

王世隆  王言章  随阳轶  王琦  林君 《地球物理学报》2011,54(9):2397-2406

直升机间域航空电磁法(Helicopter-borne time-domain electromagnetic method,HTEM)的多次空中仪器校准可消除飞行过程中仪器系统受外界环境的时变影响.吊舱校准装置可解决地面环线方式无法实现的空中飞行过程中仪器校准问题.本文从研究同心补偿吊舱装置模型出发,提出了吊舱装置空...  相似文献   

基于异常线圈的时间域AEM系统测试和标定方法研究   总被引：3，自引：2，他引：1       下载免费PDF全文

嵇艳鞠  李肃义  于生宝  朱凯光  周逢道  王言章  王世隆  刘焕江  任广群  林君 《地球物理学报》2011,54(10):2690-2697

为了检验和测试时间域航空电磁系统的测量精度和有效性,采用地面铺设闭合的异常线圈模拟地下有限导体的方法,将异常线圈的电磁响应理论值与系统实测数据进行拟合分析,来确定系统误差和飞行几何参数误差.在计算异常线圈电磁响应的基础上,研究了衰减曲线、剖面曲线与线圈的电性、几何参数关系,设计了野外测试实验方案.在长春市大鹅岛附近,采用吊车进行了系统测试,测试结果表明:单点实测数据的平均绝对误差为0.48 mV,系统相对误差小于1%,飞行高度误差为0.4 m、水平偏移误差为0.2 m.基于异常线圈进行时间域航空电磁系统的测试和标定,是一种准确、快速、经济可行的方法,具有野外施工便捷、参数调整灵活等特点,适用于任何时间域电磁测量系统的检测.  相似文献   

Correlation failure analysis of an uncertain hysteretic vibration system     

张旭方  张义民  郝秋菊 《地震工程与工程振动(英文版)》2008,7(1):57-65

In this paper, a numerical method for correlation sensitivity analysis of a nonlinear random vibration system is presented. Based on the first passage failure model, the probability perturbation method is employed to determine the statistical characteristics of failure modes and the correlation between them. The sensitivity of correlation between failure modes with respect to random parameters characterizing the uncertainty of the hysteretic loop is discussed. In a numerical example, a two-DOF shear structure with uncertain hysteretic restoring force is considered. The statistical characteristics of response, failure modes and the sensitivity of random hysteretic loop parameters are provided, and also compared with a Monte Carlo simulation.  相似文献   

岩体隧道锚固作用分析     

李新平  宋桂红  刘巍  彭元平 《岩土力学》2005,26(Z2):131-135

在工程实例中利用数值模拟方法对考虑和不考虑松动圈的岩体,在不同工况下锚杆加固前后的径向、环向应力,径向、环向位移以及锚杆轴向应力进行全面比较分析。研究锚杆和松动圈对隧洞围岩力学性质的影响,结果表明考虑和不考虑松动圈相比,洞室表面径向位移要明显大一些,而且外界载荷越大,二者的差值越大;在锚杆加固作用下环向应力峰值无论是否考虑松动圈,其出现位置都较加固前向洞壁方向移动,同时围岩径向位移在加固前后变化很大,随着外界载荷的增大,径向位移减小越明显。锚杆支护的主要作用之一是控制围岩的变形和发展,通过锚杆加固改善应力环境来提高围岩的稳定性。  相似文献   

拦沙环工程抗风蚀性能研究   总被引：4，自引：3，他引：1  

李宏  赵爱国  庄维健  王宏涛 《中国沙漠》2004,24(2):252-256

拦沙环治沙是一种新的治沙、防沙、抗风蚀技术。其利用风沙搬运功能, 将拦截到的沙子筑成拦沙大坝, 并且不断提升和拦截, 从而实现以沙治沙目的。通过在野外风沙环境风洞内, 对不同尺寸规格的拦沙环在不同风速条件下进行测试。并计算积沙量、观察和分析其拦沙效应、抗风蚀性能, 从而最终得出该技术可行性的结论。  相似文献   

不受地理位置限制的地热和太阳能联合发电系统   总被引：2，自引：0，他引：2  

周刚  倪晓阳  李金锋 《地球科学》2006,31(3):394-398

为解决能源问题,开发可再生能源,利用闭式循环将地热系统和太阳能系统联合起来发电.发电系统可以避免因大规模开发利用地热水资源可能造成的地震、地面沉降、地热水资源衰减、地热水有害成分污染、热污染等环境问题,也可以克服地热发电和太阳能发电受地理位置限制的缺点.地热系统地下部分由两垂深3～5km的井在井底由一5～7km的水平井连接而成,水平井中流体温度可达150℃左右,适合于ORC发电.太阳能系统采用槽式聚光镜集热,集热流体可选水或油,最高温度可达350℃以上.ORC一级循环工质为水,二级循环工质为异丁烷;ORC发电效率,白天最大为20%,晚上最大为12%.系统采用化学储能,储能密度为显热储能和潜热储能的10倍以上.钻井和完井、太阳能热能转换、载热流体、ORC和储能等技术的研究结果证明该系统是可行的.  相似文献   

地下闭式循环地热交换发电系统简介     

周刚  李金锋  Helmut WOLFF  汤凤林 《地质科技情报》2006,25(4):105-108

为解决能源问题而提出了地下闭式循环地热交换发电系统.该系统地下部分通过全井下套管形成一个封闭系统,克服了传统地热发电和干热岩发电受地质条件制约、对环境造成危害等缺点,是一种新型的不依赖位置、环境友好的地热发电系统.采用大位移技术进行钻井,应用悬链线技术对井身剖面结构进行了优化,提出了地下连接技术要求,应用分支井和膨胀套管技术固井,设计了水泥配方并进行了相关试验,优化了载热流体,计算了有机工质朗肯循环(ORC)的发电效率.  相似文献